The invention relates to the lost foam process for metal casting, and more particularly to foam pattern assemblies used in the lost foam casting process and to the preparation of foam pattern assemblies for casting.
The lost foam casting process typically includes the steps of dipping a foam pattern or pattern cluster in a refractory coating with the sprue extending upwardly, and drying the pattern by hanging it by the sprue. This can present a problem if the pattern has a pocket which opens upwardly when the sprue extends upwardly, since, even if the pattern is turned upside down to empty the pocket, some refractory coating will collect in the bottom of the pocket when the pattern is turned rightside up for drying. This results in an unnecessarily thick coating which is more difficult to dry and which can cause casting defects.
Attention is directed to the following U.S. patents:
______________________________________ Miner 2,731,668 Jan. 24, 1956 Robb et al. 2,755,205 July 17, 1956 Tingquist et al. 3,278,998 Oct. 18, 1966 Edwards et al. 4,240,492 Dec. 23, 1980 Cole 4,396,054 Aug. 2, 1983 ______________________________________